Reproductive System BIOL 163 PDF

UNIT 8 HUMAN DEVELOPMENT AND THE CONTINUITY OF LIFE BIOL 163 (Human Anatomy and Physiology) Department of Biology College of Mathematics and Natural Sciences Caraga State University  UNIT 8.1 Reproductive System (Anatomy and Phys...

UNIT 8 HUMAN DEVELOPMENT AND THE CONTINUITY OF LIFE BIOL 163 (Human Anatomy and Physiology) Department of Biology College of Mathematics and Natural Sciences Caraga State University  UNIT 8.1 Reproductive System (Anatomy and Physiology of the Male and Female Reproductive System) Learning Outcomes: * Identify the organs of the male and female reproductive system and its general function. * Discuss the composition of the semen and name the glands that produce it. * Trace the pathway followed by a sperm from the testis to the body exterior. * Define circumcision, erection, and ejaculation. * Describe the effects of hormones in reproductive function. * Discuss the process of oogenesis and spermatogenesis. 3  Male Reproductive System: - is a group of organs and structures responsible for the production, storage, and delivery of sperm and the production of male sex hormones, primarily testosterone. It consists of external and internal components, which work together to ensure reproductive functions. Reproductive functions: 1. Sperm production 2. Semen production 3. Hormone production 4. Reproduction 4 Male Reproductive System: Parts Function Penis Organ for copulation and excretion of urine. Delivers sperm into the female reproductive tract. Scrotum Protects and regulates the temperature of the testes for optimal sperm production. Testes Produces sperm (spermatogenesis) and testosterone. Epididymis Stores and matures sperm. Vas deferens Transports sperm from the epididymis to the ejaculatory duct. Ejaculatory Channels sperm and seminal fluid into the urethra. ducts Urethra Serves as a passage for urine and semen to leave the body. Seminal Produce seminal fluid rich in fructose to nourish vesicles sperm. Prostate Secretes fluid that enhances sperm motility and gland viability Bulbourethral Produce pre-ejaculatory fluid to lubricate the urethra glands and neutralize acidity. 5 Male Reproductive Microscopic Anatomy of Penis System: Histological Features: Erectile Tissues: Corpora Cavernosa: Two cylindrical structures responsible for erection. Corpus Spongiosum: Surrounds the urethra and prevents its compression during erection. Tunica Albuginea: A dense connective tissue layer surrounding the erectile tissues, providing structural support. Vascular and Nervous Supply: Highly vascularized with helicine arteries and Transverse section of the penis venous spaces. (2x). Rich in nerve endings for sensory and autonomic functions. Urethra: Lined by stratified or pseudostratified columnar epithelium, transitioning to stratified squamous near the external opening. Skin and Subcutaneous Tissue: Cross-sectional view of a seminal Thin, elastic, and contains sebaceous glands. gland with its elaborate network of Prepuce (foreskin) offers additional protection. mucosal folds. Glandular secretion is seen in the lumen (25x). Cross section of epididymis (120x). 6  Male Reproductive Microscopic Anatomy of selected organs System: Testis - the primary male reproductive organ responsible for sperm production and testosterone secretion. Histological Features: Seminiferous Tubules: Site of sperm production (spermatogenesis). Lined by germinal epithelium with Sertoli cells providing support and nourishment to developing sperm cells. Interstitial Tissue: Contains Leydig cells that produce testosterone. Rich in blood vessels and connective tissue. Tunica Albuginea: A fibrous capsule enclosing the testis. Supporting Cells: Sertoli Cells: Provide structural and metabolic support to germ cells. Leydig Cells: Secrete androgens, primarily testosterone. 7  Spermatogenesis - The process of sperm cell development Spermatogenesis from diploid germ cells to haploid spermatozoa. Stages of Spermatogenesis: 1. Spermatogonial Phase (Mitosis): Spermatogonia (diploid) divide to produce more spermatogonia and primary spermatocytes. 2. Spermatocyte Phase (Meiosis): Primary spermatocytes undergo meiosis I to form secondary spermatocytes (haploid). Secondary spermatocytes undergo meiosis II to form spermatids. 3. Spermatid Phase (Spermiogenesis): Spermatids transform into mature spermatozoa. Supporting Cells: 4. Sertoli Cells: Nourish and support developing sperm cells. Create the blood-testis barrier to protect germ cells. Hormonal Regulation: 5. FSH: Stimulates Sertoli cells and supports spermatogenesis. 6. LH: Stimulates Leydig cells to produce testosterone. 7. Testosterone: Promotes sperm maturation. Duration: Approximately 64-72 days for a full cycle. 8 Circumcision Definition: Circumcision is a surgical procedure in which the foreskin (the retractable fold of skin covering the head of the penis) is removed. Purpose: It may be performed for cultural, religious, or medical reasons. Medical benefits can include a reduced risk of certain infections and improved hygiene. 9 Erection 10  Erection Anatomy of Penis: The penis consists of three columns of erectile tissue: two corpora cavernosa (located dorsally) and one corpus spongiosum (located ventrally, surrounding the urethra). The glans penis is the bulbous tip, which is sensitive and plays a role in sexual pleasure. Neurovascular Mechanism Neural Stimulation: Erection is initiated by sexual arousal, which leads to stimulation of the parasympathetic nervous system. This causes the release of neurotransmitters like nitric oxide (NO). Nitric Oxide (NO): NO triggers the relaxation of the smooth muscle in the walls of the arteries supplying the penis. This relaxation allows more blood to flow into the erectile tissues. Vascular Changes Increased Blood Flow: Blood flow into the corpora cavernosa increases significantly during sexual arousal. This causes the corpora cavernosa to expand, compressing the surrounding veins and limiting the outflow of blood, thereby maintaining the erection. Compression of Veins: The engorgement of the erectile tissue compresses the venous drainage, trapping blood inside the penis and leading to rigidity. Role of the Endothelium The endothelial cells of blood vessels in the penis release nitric oxide (NO), a vasodilator that helps in the relaxation of smooth muscle, thus promoting blood flow and causing the erection. 11 Erection Mechanism of Detumescence (Loss of Erection) After ejaculation or cessation of sexual arousal, the sympathetic nervous system is activated, leading to the contraction of smooth muscle in the arteries and venous return. This results in reduced blood flow into the penis, causing detumescence (loss of erection). Factors Affecting Erection Physical Factors: Age, hormonal levels (testosterone), and blood circulation can impact erectile function. Conditions like diabetes, hypertension, and atherosclerosis can impair blood flow and contribute to erectile dysfunction. Psychological Factors: Stress, anxiety, and mental health conditions can inhibit the process of erection. Emotional connection and mental stimulation also play key roles. 12 Ejaculation: Pathway of the Sperm from the Testis to the body exterior 1 MATURATION Sperm mature in the epididymis 2 STORAGE AND TRANSFER Muscle contractions cause sperm to move from epididymis through the Vas deferens 3 DELIVERY At ejaculation, approximately Sperm move through the 300 million sperm cells are expelled as part of a fluid, called semen. ejaculatory duct into the urethra, where they can be expelled. 13 Male Hormones: 14 Structure Description Function Ovaries Small, oval-shaped Produce ova (eggs) Female Reproductive System: organs containing and secrete follicles that house hormones (estrogen oocytes. and progesterone). Fallopian tubes Tubes lined with Facilitate the ciliated epithelium; transport of ova from divided into ovaries to the uterus; infundibulum, site of fertilization in ampulla, and the ampulla. isthmus. Uterus A hollow, muscular Supports and organ with three nourishes a fertilized layers: perimetrium, egg; site of myometrium, and implantation and fetal endometrium. development. Cervix Narrow, cylindrical Produces cervical structure connecting mucus; allows the uterus to the passage of sperm vagina. into the uterus; acts as a birth canal during labor. Vagina A fibromuscular canal Receives the penis lined with stratified during intercourse; squamous serves as a conduit epithelium. for menstrual flow and childbirth. 15 Female Reproductive System: Vulva - encompasses the external female genitalia and plays roles in reproduction, protection, and sexual sensation. Functions: Protects internal reproductive organs. Facilitates sexual arousal and lubrication. Provides an opening for the passage of urine and menstrual flow. Anatomical Structures: Mons Pubis: Fatty tissue covering the pubic bone. Labia Majora: Outer folds of skin containing sweat and sebaceous glands; protect internal structures. Labia Minora: Inner folds of skin; enclose the vestibule and contain blood vessels and nerve endings. Clitoris: Erectile tissue rich in nerve endings; primary structure for sexual sensation. Vestibule: Area enclosed by the labia minora, containing the urethral and vaginal openings. Bartholin's Glands: Glands near the vaginal opening that secrete mucus for lubrication. Perineum: Area between the vaginal opening and anus. 16 Female Reproductive System: Broad Ligament A double layer of peritoneum that supports the uterus, ovaries, and fallopian tubes in the pelvic cavity. Subdivisions: Mesometrium: Supports the uterus. Mesosalpinx: Encloses and supports the fallopian tubes. Mesovarium: Suspends the ovaries. Fundus of the Uterus The rounded, uppermost portion of the uterus above the openings of the fallopian tubes. Function: Provides space for embryo implantation and expansion during pregnancy. 17 Female Reproductive System: Uterine Tube (Fallopian Tube) Divided into four sections: Infundibulum: Funnel-shaped, near the ovary; contains fimbriae that capture the ovum. Ampulla: Widest section; typical site of fertilization. Isthmus: Narrow section connecting to the uterus. Interstitial (Intramural): Passes through the uterine wall into the uterine cavity. Wall of the Uterus Composed of three layers: Perimetrium: Outer serous layer, part of the peritoneum. Myometrium: Thick muscular layer responsible for contractions during labor. Endometrium: Inner mucosal layer, site of implantation, and menstruation. 18 Female Reproductive System: Oogenesis - is the process of egg (ovum) formation in the ovaries, beginning before birth and continuing until menopause. 2. Stages of Oogenesis Prenatal Phase: Primordial germ cells undergo mitosis to form oogonia. Oogonia differentiate into primary oocytes and begin meiosis I, which is arrested in prophase I until puberty. Puberty to Menopause: During each menstrual cycle, some primary oocytes complete meiosis I, forming: Secondary oocyte: Receives most of the cytoplasm. Key Features First polar body: A small, non-functional cell. Oogenesis produces one functional ovum and three polar bodies from each The secondary oocyte begins meiosis II, arrested at primary oocyte. It is regulated by FSH, LH, and estrogen. metaphase II until fertilization. Only about 400-500 oocytes are ovulated during a woman’s reproductive Fertilization: life. If fertilized, the secondary oocyte completes meiosis Comparison to Spermatogenesis II, forming: Oogenesis produces a single mature ovum, while spermatogenesis results Ovum: A mature egg. in four functional spermatozoa per germ cell. Second polar body: Another small, non-functional cell. 19  Ovarian Cycle - refers to the series of events that occur in the ovaries during a woman’s menstrual cycle, responsible for the maturation of oocytes and the preparation of the uterus for pregnancy. 2. Phases of the Ovarian Cycle Follicular Phase (Day 1-14): Begins with the Menstrual Phase of the uterine cycle. FSH stimulates the growth of primary follicles into secondary follicles. Dominant follicle matures and secretes estrogen. Estrogen promotes thickening of the endometrium in preparation for implantation. Ends with ovulation. Ovulation (Day 14): Surge of LH (Luteinizing Hormone) triggers the release of the mature ovum from the dominant follicle. The follicle ruptures, releasing the egg into the fallopian tube, where fertilization may occur. 20  Ovarian Cycle - Luteal Phase (Day 15-28): The ruptured follicle transforms into the corpus luteum, which secretes progesterone. Progesterone further prepares the endometrium for implantation and maintains pregnancy if fertilization occurs. If fertilization does not occur, the corpus luteum degenerates, leading to a drop in progesterone and estrogen levels, and the cycle repeats. 3. Hormonal Regulation FSH: Stimulates follicle growth in the follicular phase. LH: Triggers ovulation and formation of the corpus luteum. Estrogen: Secreted by the developing follicles; stimulates endometrial growth. Progesterone: Secreted by the corpus luteum; supports endometrial preparation for pregnancy. 21  Mammary Gland A specialized exocrine gland responsible for the production of milk (lactation). Found in both males and females, but functional only in females, particularly during and after pregnancy. Anatomy of the Lactating Mammary Gland Lobes and Lobules: The mammary gland is divided into lobes, which contain smaller lobules where milk production occurs. Each lobe is connected to a duct system that drains into the nipple. Alveoli: Small, sac-like structures within the lobules, where milk is produced. Alveoli are lined by milk-secreting epithelial cells and surrounded by myoepithelial cells that contract to help expel milk. Milk Ducts: Ducts collect milk from the alveoli and carry it towards the nipple. Larger ducts are called lactiferous ducts, which converge into lactiferous sinuses near the nipple. Nipple and Areola: The nipple contains pores through which milk is released Hormonal Regulation of Lactation during breastfeeding. Prolactin: Stimulates milk production in the alveoli. The areola is the pigmented area surrounding the nipple, Oxytocin: Stimulates the contraction of myoepithelial cells to expel milk which contains sebaceous glands (Montgomery's glands) from the alveoli through the ducts. that secrete lubricating fluid. 22 Female Hormones: 23  UNIT 8.2 Reproductive System (Female Reproductive Functions and Cycle Pregnancy and Embryonic Development) Learning Outcomes: * Define fertilization and zygote. * Describe implantation. * List the major functions of the placenta. * Indicate several ways that pregnancy alters or modifies the function of the mother’s body. * Identify several agents that can interfere with normal fetal development. * Describe how labor is initiated and briefly discuss the three stages of labor. * Discuss common pathological issues concerning the reproductive system. 25 Female Reproductive Function: Fertilization Fertilization is the process by which a sperm cell from the male merges with an egg (ovum) from the female, resulting in the formation of a zygote. Process of Fertilization Sperm Capacitation: Sperm undergo changes in the female reproductive tract, making them capable of fertilizing the egg. This includes the loss of surface proteins and increased motility. Sperm Navigation: Sperm travel through the cervix, uterus, and fallopian tubes to reach the egg. Chemotaxis guides sperm toward the egg using chemical signals released by the egg. Penetration of the Egg: The sperm must break through the corona radiata (a layer of cells surrounding the egg) and the zona pellucida (the egg's protective glycoprotein layer). The sperm releases enzymes from its acrosome to digest the zona pellucida. Formation of the Zygote Fusion of Sperm and Egg Membranes: The sperm and egg nuclei fuse, combining their genetic material. Once the sperm penetrates the zona pellucida, its plasma membrane The resulting zygote is a diploid cell, containing a full set of fuses with that of the egg. chromosomes (23 pairs in humans). The sperm nucleus enters the egg, leading to the formation of the zygote. Importance of Fertilization Block to Polyspermy: Fertilization is essential for the continuation of the species, initiatin After the sperm enters the egg, changes in the egg's membrane prevent the process of embryonic development, which will eventually lead additional sperm from entering, ensuring only one sperm fertilizes the egg. pregnancy. 26 Female Reproductive Function: Implantation Implantation is the process by which a fertilized egg (zygote) attaches to the lining of the uterus (endometrium) and begins to develop into an embryo. 2. Stages of Implantation Day 1-5: Early Development and Transport After fertilization, the zygote begins dividing, forming a blastocyst as it moves down the fallopian tube toward the uterus. Day 5-7: Apposition and Adhesion The blastocyst reaches the uterus and aligns itself with the endometrium. The outer layer of the blastocyst (the trophoblast) begins to attach to the endometrial lining. The trophoblast cells secrete enzymes that allow them to penetrate the endometrial tissue. Day 7-10: Invasion and Embedding The trophoblast continues to invade the endometrial lining, forming villi that grow into the uterine wall. As the trophoblast invades, it forms the early stages of the placenta, which will provide nutrients and remove waste for the developing embryo. Day 10-14: Complete Implantation By Day 10, the blastocyst is completely embedded in the endometrium, and the placenta begins to develop further, ensuring that the embryo is nourished. The corpus luteum continues to secrete progesterone to maintain the endometrial lining and prevent menstruation. 3. Hormonal Regulation Human Chorionic Gonadotropin (hCG): After implantation, the trophoblast cells secrete hCG, which signals the corpus luteum to continue progesterone secretion, maintaining 27 Female Reproductive Function: Implantation Hormonal Regulation Human Chorionic Gonadotropin (hCG): After implantation, the trophoblast cells secrete hCG, which signals the corpus luteum to continue progesterone secretion, maintaining the uterine lining. Progesterone: Progesterone supports the endometrial lining, preventing its breakdown, and helps in the continuation of pregnancy. 4. Significance of Implantation Implantation is a critical step for establishing pregnancy, as it allows for the formation of the placenta and the continued development of the embryo. 28 Placenta Female Reproductive Function: - It is fetomaternal organ functions to support fetal development. - 2 components: Fetal part- develops from the chorionic sac (chorion frondosum) Maternal part- derived from the endometrium (functional layer- decidua basalis) - Placenta and umbilical cord- are a transport Development of the Placenta The placenta begins developing after implantation and reaches full maturity by the end of the first trimester, enabling efficient nutrient and waste exchange for the growing fetus. system for substances between the mother and the fetus. 29 Placenta Female Reproductive Function: Placental Blood Flow Maternal Circulation: Blood from the mother flows through spiral arteries into the intervillous space, surrounding the villi. Fetal Circulation: Oxygenated blood returns to the fetus via the umbilical vein, while deoxygenated blood is carried from the fetus to the placenta through the umbilical arteries.. Development of the Placenta The placenta begins developing after implantation and reaches full maturity by the end of the first trimester, enabling efficient nutrient and waste exchange for the growing fetus. 30 Female Reproductive Function: Placenta Functions of the Placenta Nutrient and Gas Exchange: The placenta allows the exchange of oxygen, carbon dioxide, nutrients, and waste products between the maternal and fetal bloodstreams without direct blood mixing. Hormonal Secretion: The placenta secretes hormones critical for maintaining pregnancy and fetal development: Human Chorionic Gonadotropin (hCG): Supports the corpus luteum in the early stages of pregnancy. Progesterone: Maintains the uterine lining and inhibits uterine contractions. Estrogen: Stimulates the growth of the uterus and prepares the body for labor. Human Placental Lactogen (hPL): Helps in fetal growth and prepares the breasts for lactation. Immune Protection: The placenta acts as a barrier to many harmful substances and microorganisms, though it allows the passage of maternal antibodies to protect the fetus. 31  Pregnancy Hormonal changes: 32  Pregnancy Body changes: -Cardiovascular System: Blood volume increases by 30–50% to supply the placenta and fetus. Heart rate increases to accommodate the greater demand for oxygen and nutrients. Some women experience swelling due to fluid retention. -Digestive System: Hormonal changes slow down digestion, often causing nausea, heartburn, and constipation. The growing uterus can compress the stomach and intestines, exacerbating these symptoms. -Respiratory System: Breathing rate may increase as the body requires more oxygen for the mother and fetus. The diaphragm moves upward due to the expanding uterus, which can cause shortness of breath. -Skeletal System: The pelvis widens, and ligaments become more flexible to prepare for childbirth. The center of gravity shifts, potentially causing back pain and changes in posture. -Skin Changes: Stretch marks may develop due to rapid growth of the abdomen and breasts. Hyperpigmentation (e.g., linea nigra, darkening of nipples, or melasma) is common. Increased oil production can lead to acne for some women. -Urinary System: The kidneys work harder to filter increased blood volume. The growing uterus may compress the bladder, leading to more frequent urination. -Breasts: Enlargement as a milk ducts and iits fat tissue increase. Nipples and areolas darken and may become more sensitive. Colostrum (a nutrient-rich pre-milk fluid) may leak during late pregnancy. 33 Female Reproductive Function: Agents interfere normal fetal development Medications and Drugs Critical Periods of Development: Certain Alcohol stages of pregnancy, particularly the first Tobacco trimester, are more sensitive to teratogenic Infections effects. This is when organ systems are Environmental chemicals developing, and exposure to harmful agents and toxins Maternal Health can cause structural malformations. conditions Dose-Response Relationship: The severity of the teratogenic effect is often related to the dose of the agent and the length of exposure during pregnancy. 34 How Labor is Initiated? 35  Three stages of Labor Stage 1: Dilation Duration: This is the longest stage, lasting from several hours to over 20 hours, especially for first-time mothers. Process: Begins with regular uterine contractions and ends when the cervix is fully dilated (10 cm). The cervix effaces (thins) and dilates to allow the baby to move into the birth canal. Phases: Latent Phase: Slow cervical dilation with mild contractions. Active Phase: Rapid cervical dilation (3-10 cm) with stronger, more frequent contractions. Pain Management: May include breathing techniques, epidural anesthesia, or other pain-relief methods. Stage 2: Expulsion Duration: Typically lasts 20 minutes to 2 hours. Process: Begins when the cervix is fully dilated and ends with the delivery of the baby. Strong, frequent contractions help push the baby through the birth canal. Mother’s Role: Active pushing efforts by the mother complement the uterine contractions. Events: The baby's head crowns (becomes visible). The baby is delivered, often headfirst (cephalic presentation). Stage 3: Placental Delivery Duration: Lasts about 5-30 minutes after the baby is born. Process: Involves the detachment and expulsion of the placenta (afterbirth) from the uterine wall. The uterus continues to contract to help expel the placenta and minimize blood loss. Medical Attention: The placenta is examined to ensure it is delivered intact to avoid complications. 36  Pathological Issues Male Reproductive Disorder -Prostate Disorders: 1. Benign Prostatic Hyperplasia (BPH): - Non-cancerous enlargement of the prostate gland, common in older men. - Symptoms include difficulty urinating, frequent urination, and weak urine flow. 2. Prostate Cancer: -One of the most common cancers in men. -Early stages may be asymptomatic; later symptoms include urinary issues and pain during ejaculation. - Erectile Dysfunction (ED): The inability to achieve or maintain an erection sufficient for sexual intercourse. Can be caused by psychological issues, vascular problems, or diabetes. - Testicular Disorders: Testicular Cancer: - Affects young to middle-aged men; early detection has a high survival rate. - Symptoms include a lump in the testicle and changes in size or shape. Varicocele: - Enlargement of veins in the scrotum, which can affect fertility. Orchitis: -Inflammation of the testicles, often caused by viral infections like mumps. - Infertility: May result from low sperm count, poor sperm motility, or blockages in the reproductive tract. 37  Female Reproductive Disorder Pathological Issues - Polycystic Ovary Syndrome (PCOS): A hormonal disorder characterized by irregular menstrual cycles, excess androgen - Ovarian Cysts: levels, and cysts on the ovaries. Fluid-filled sacs on the ovaries that may cause pain or menstrual Associated with infertility, weight gain, and irregularities. an increased risk of diabetes. Most cysts are benign and resolve on their own, but some may - Endometriosis: require surgical removal. Occurs when tissue similar to the uterine - Cancers: lining grows outside the uterus. Cervical Cancer: Often caused by persistent infection with the Symptoms include pelvic pain, painful human papillomavirus (HPV). menstruation, and infertility. Ovarian Cancer: Typically diagnosed at advanced stages due to - Pelvic Inflammatory Disease (PID): vague symptoms. Infection of the female reproductive organs, Uterine (Endometrial) Cancer: Common in postmenopausal often caused by sexually transmitted women; presents as abnormal bleeding. infections (STIs) like chlamydia or - Infertility: gonorrhea. Caused by hormonal imbalances, blockages in the fallopian Can lead to chronic pelvic pain and infertility tubes, or conditions like PCOS or endometriosis. if untreated. - Uterine Fibroids: Non-cancerous growths in the uterus. May cause heavy menstrual bleeding, pelvic pain, and pressure on the bladder. 38 Thank you!